A245998 Number of length 3+2 0..n arrays with no pair in any consecutive three terms totalling exactly n

2, 18, 164, 676, 2262, 5766, 13064, 25992, 48170, 82810, 135852, 212268, 320894, 468846, 668432, 929296, 1267794, 1696482, 2236340, 2903220, 3723302, 4716118, 5913624, 7339416, 9031802, 11018826, 13345724, 16045372, 19170510, 22759230

Offset

1,1

Comments

Row 3 of A245995

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 3*a(n-1) -8*a(n-3) +6*a(n-4) +6*a(n-5) -8*a(n-6) +3*a(n-8) -a(n-9).

Empirical: G.f.: 2*x*(1+6*x+55*x^2+100*x^3+183*x^4+86*x^5+49*x^6) / ( (1+x)^3*(x-1)^6 ). - R. J. Mathar, Aug 10 2014

Example

Some solutions for n=10
..6....9....2....7....1...10....9....7....9....9....3....5....1....5....5....6
..8....9....7...10....4....8....8....9...10....6....9....6....5....6....8....1
..3...10...10....9....3....4...10....0....3....2....2....1....2....7....3....5
..6....2....5....4....2....9...10....3....2...10....4....2....1....2....5....1
..3....2...10....4....9...10....6....0....9....9...10....3....7....1....8....0

Crossrefs

Sequence in context: A144513 A037518 A037721 * A005260 A183250 A037728

Adjacent sequences: A245995 A245996 A245997 * A245999 A246000 A246001

Keyword

nonn

Author

R. H. Hardin, Aug 09 2014

Status

approved